1. Field of the Invention
The present invention relates to a focus voltage control apparatus adapted for application to a color CRT (cathode-ray tube) display for use in computer graphics or the like.
2. Description of the Related Art
In a color CRT display for computer graphics, it is generally customary that a focus voltage is so set as to attain a just focused state with respect to a green color because of the fact that the human visual attribute is the most sensitive to green. Under the condition where green is seen distinctly, any other individual colors and compounds thereof are also seen relatively distinctly.
However, in such color CRT display where the focus voltage is set in conformity with green, there exists a problem that when any other single color than green, such as blue or red, is used for displaying characters or the like, the displayed image is rendered indistinct.
The focus voltage is adjustable, depending on any specific purpose of use of the color CRT display or the individual destination area thereof, by selectively changing the color to attain a desired just focused state, but high skill is necessary for such adjustment with another disadvantage that the required labor is not negligible.